Did you miss out on the black borders for your Scalextric Classic or Sport track that had the flat kerbs (curbs)? Were you not able to procure enough of them for your layout? Or, did you need the R1 outer as a flat kerb, which Scalextric never even produced? If you still have the bump kerbs with the red and white stripes, and are tired of your performance cars getting upset by the transition over that bump, then fret no more! Just print these up and put them in place of the bump curbs (kerbs).
I have updated all the models (and added some more) to have the same type of tabs as OEM border kerb inserts have. Depending on the method of printing, however, the "vertical" tabs can be very fragile, and easily snap off during installation. The BEST way to install the kerbs is to first insert those vertical tabs, and then CAREFULLY bend the border while holding the kerb firmly in place, so that the horizontal tabs can pop into place. If the tabs break, just keep proceeding with the installation, and they may still hold in place fairly well.
If the tabs break and the borders keep coming out of the slot, you'll need to glue them in place. Hot glue works well. I have printed and test fitted all these pieces, and they fit well.They have also been serving long term on a couple other tracks in my clubs.
My personal preference when printing these is to print them top down (as provided) on a textured build plate to give the top of the border a nice texture. Any type of filament should be fine. There is no need to spend extra on "strong" filament. Print them with whatever you like the look of best.
Update 3/9/2020: Changed the text on each model from my name to my initials plus piece ID. e.g. "R2O" is an insert for an R2 outside border. Update 4/3/2020: Added parts for Right and Left pit lane borders. There are single parts for R and L if your plate is large enough, as well as 2 parts for each side. Keep an eye on this thing, because I'm planning to update the two part pit lane insert, as well as the lead in/out inserts.